Down syndrome is a condition that results in intellectual disability of varying degrees and may cause physical problems such as heart defects, or difficulties with the sight and hearing.

About 1 in 700 babies born in New South Wales will have Down syndrome.

Your midwife or obstetrician (a doctor who specialises in pregnancy and childbirth) will let you know if you need any extra scans.

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A change in the level of these proteins may indicate that there is an increased risk that the baby has Down syndrome.

The ultrasound can be done by a specially trained sonologist or sonographer between 11.5 and 14 weeks of pregnancy.

The ultrasound allows measurement of the amount of fluid in the skin at the back of the baby’s neck. All babies at this stage in pregnancy have some fluid in this area, but a baby with Down syndrome or another chromosome abnormality tends to have more fluid.

The ultrasound also double checks The nuchal translucency test can be done between 11.5 and 14 weeks of pregnancy (ideally at 12-13 weeks).

All women have a risk of having a baby with Down syndrome, although this risk increases with the age of the woman. It is caused by having 3 rather than 2 copies of chromosome number 21.

The test has two parts: There is no risk to the baby from either of these procedures.

This is more accurate than each test done by itself.

It is very important to realise that this test is only for Down syndrome and that a ‘low risk’ result does not ensure that the baby is free of other possible birth defects.

In order to receive the results on the day of the ultrasound, the blood test must be taken at least a few days before the ultrasound, preferably at 10 weeks.